U.S. Pat. No. 3,843,076 discloses a terminal guidance scheme which differs from the present invention in that: (1) it is an active system requiring a light source, rather than a passive system which senses ambient radiation; (2) it is not capable of performing imaging; (3) it does not employ TDI (Time Delay Integration); (4) it is designed for use just on a missile rather than an airplane or other vehicle; and (5) it is a seeker used for one target, rather than a searcher which searches for several targets.
U.S. Pat. No. 4,397,430 discloses a homing system having a sensor which differs from the present invention in that: (1) constant sensitivity is not achieved for all points within the viewed scene (see FIG. 6) because the detector elements towards the middle of circle 4 observe the scene for a longer period of time than those towards the edge; (2) TDI is not employed; and (3) the detector comprises a single row of detector elements rather than a focal plane array comprising several rows of detector elements.
U.S. Pat. No. 4,193,688 discloses an optical scanning system which differs from the present invention in that: (1) the detector comprises a single row of detector elements, rather than a focal plane array comprising several rows of detector elements; (2) the detector does not attain constant sensitivity at all points in the viewed scene; and (3) TDI is not performed.
U.S. Pat. No. 4,227,077 discloses an optical tracking system which differs from the present invention in that: (1) it comprises a nutating seeker and tracker, as opposed to a rotating sensor; (2) it does not employ TDI; and (3) it uses hexagonally spaced detectors, as opposed to a focal plane array having the shape of a sector of a figure formed by up to two conic sections.
Secondary references are U.S. Pat. Nos. 3,318,650 and 4,537,370.